Image Coding and Decoding Method and Device

ABSTRACT

An image coding method and apparatus and an image decoding method and apparatus are provided by the present document. The image coding method includes: implementing matching coding for pixels of an input video image to obtain one or more matching relationship parameters, herein the matching relationship parameters are parameters used in a process of constructing predicted values and/or reconstructed values of the pixels in the image; mapping the matching relationship parameters to obtain mapped values of the matching relationship parameters; and performing entropy coding on the mapped values of the matching relationship parameters. The present document addresses the problem existing in the conventional art which is caused by the direct implementation of entropy coding for matching relationship parameters and achieves a good data compression effect through entropy coding.

TECHNICAL FIELD

The present document relates to compression coding and decoding ofdigital videos, and in particular to image coding and decoding methodsand apparatus.

BACKGROUND

The natural form of digital video signals of images is a sequence ofimages. Generally, an image is a rectangular region consisting of aplurality of pixels, if 50 images are recorded per second in a digitalvideo signal, then a 30-minute digital video signal is a video imagesequence consisting of 90000 images, that is, 30*60*50 images, in somecases, video image sequence is called video sequence or sequence forshort. Coding a digital video signal is actually coding images one byone.

According to the latest international video compression standard HighEfficiency Video Coding (HEVC), in the coding of an image, the image isdivided into a plurality of sub-images of M*M pixels, a sub-image iscalled a coding Unit (referred to as a CU for short), and the sub-imagesare coded one by one by taking CU as the basic coding unit. Commonly,the value of M is 4, 8, 16, 32 or 64. Therefore, coding a video imagesequence is coding various coding units in various frames successively.Similarly, decoding a video image sequence is also decoding variouscoding units in various frames successively with the same order, therebyreconstructing the whole video image sequence. HEVC codes an image in apredictive coding way. First, the predicted value of the pixels in aninput video image is constructed according to coded image information,and then the difference between the predicted value and the originalvalue of the pixel in the input video image is coded, at the same time,the parameters needed for constructing the predicted value need to becoded. In a decoding process, first, the predicted value of the pixel inan image to be decoded is constructed according to the parametersacquired from a bitstream and decoded image information, and then thesum of the predicted value that may be subjected to a filteringprocessing and a difference value acquired from the bitstream is used asthe reconstructed value of the pixels in the current image to bedecoded. It should be noted that a method similar to that in thedecoding process also needs to be used in a coding process itself toconstruct the local decoding reconstructed values of the input videoimage for constructing prediction references of the predicted values ofthe pixels in the following input video image.

As each portion of an image is different in content and nature, toachieve the optimal coding performance, the sizes of the CUs in an imagemay be different, the sizes of some CUs may be 8*8, the sizes of someCUs may be 64*64, and so on. To splice CUs of different sizesseamlessly, an image is always divided into Largest Coding Units (LCUs)with the same size of N*N pixels first, then each LCU is further dividedinto a plurality of CUs which may be of different sizes. For example, animage is divided into LCUs with the same size of 64×64 pixels first(N=64). One LCU consists of three CUs of 32*32 pixels and four CUs of16*16 pixels. Another LCU consists of two CUs of 32*32 pixels, three CUsof 16*16 pixels and twenty CUs of 8*8 pixels. Coding an image meanssuccessively coding the CUs in successive LCUs. At any moment, the CUwhich is being coded is referred to as a CU in current coding.Similarly, decoding the image also means successively decoding the CUsin successive LCUs in the same sequence. At any moment, the CU which isbeing decoded is referred to as a CU in current decoding. A CU incurrent coding or a CU in current decoding are collectively referred toas a current CU.

A color pixel is consisted of three components. The two pixel colorformats that are used most frequently are GBR color format made up of agreen component, a blue component and a red component and YUV colorformat, for example, the YCbCr color format, which is made up of a lumacomponent and two chroma components. Therefore, to code a CU, the CU maybe divided into three component planes (planes G, B and R or planes Y, Uand V), and then the three component planes are coded separately;alternatively, the three components of a pixel may be bound into athree-component group, and then CUs composed of these three-componentgroups are coded as a whole. The former arrangement of pixels and thecomponents thereof are referred to as the planar format of an image (andthe CUs thereof), and the latter arrangement of pixels and thecomponents thereof are referred to as the packed format of an image (andthe CUs thereof).

According to whether chroma components can be downsampled, the YUV colorformat can further be subdivided into a plurality of types ofsub-formats: a YUV4:4:4 pixel color format where one pixel consists ofone Y component, one U component and one V component; a YUV4:2:2 pixelcolor format where a left pixel and an adjacent right pixel consist oftwo Y components, one U component and one V component; and a YUV4:2:0pixel color format where the four adjacent pixels that are spatiallyarranged left-to-right and up-to-down into a 2*2 array consist of four Ycomponents, one U component and one V component. Generally, a componentis represented by a numeral composed of 8-16 bits. The YUV4:2:2 pixelcolor format and the YUV4:2:0 pixel color format are both obtained byperforming a chroma component downsampling operation on the YUV4:4:4pixel color format. A pixel component is also referred to as a pixelsample or a sample for short.

In the application of the present document, pixel and pixel sample valueare both referred to as pixel value, that is, a ‘pixel value’ refers toa ‘pixel’ or a ‘pixel sample value’.

A reconstructed pixel value is generated when any CU is coded ordecoded, the reconstructed pixel value is further classified into apartially reconstructed pixel value generated from a different degree ofpartial reconstruction during a coding or decoding process and acompletely reconstructed pixel value that is generated after completingthe coding or decoding. If there is a completely reconstructed pixelvalue equal to an originally input pixel value before the coding, thenthe coding and decoding process is called lossless coding and decoding.If a completely reconstructed pixel value is different from theoriginally input pixel value before the coding, then the coding anddecoding process is called lossy coding and decoding. The reconstructedpixel values generated during the process of coding or decoding CUs insuccession are usually stored as history data used as reference pixelvalues for subsequent CU coding or decoding. A storage space for storingreconstructed pixel history data is called a temporary space ortemporary buffer for reference pixel values or a reference pixel valueset. The temporary space for reference pixel values is a limited spaceonly for storing a part of history data. The history data stored in thetemporary space for reference pixel values may also include thereconstructed pixel value of the current CU.

With the development and popularization of the new generation of cloudcomputing and information processing modes and platforms which aretypically represented by remote desktop, the interconnection among aplurality of computers, the interconnection among a computer host, asmart TV, a smart phone, a tablet personal computer and other digitaldevices, and the interconnection among a variety of digital devices havecome true and generally become the dominant trend. Thus, the real-timescreen transmission between a server side (cloud) and a user side isneeded urgently at present. Because the quantity of the screen videodata to be transmitted is very huge, computer screen images must besubjected to a high-efficiency high-quality data compression.

One of the main goals of the latest international video compressionstandard HEVC is to make the best use of the characteristics of computerscreen images to compress computer screen images highly efficiently.

A remarkable characteristic of computer screen image is the typicalinclusion of many similar or even identical pixel patterns in an image.For example, Chinese or foreign language words that are often seen in acomputer screen image are all composed of several basic strokes, manysimilar or identical strokes can be found in the same image. For themenus and icons in a computer screen image, there are also many similaror identical patterns. In the intra prediction mode adopted by existingimage and video compression technologies, only referencing adjacentpixel values makes it impossible to improve compression efficiency byutilizing the similarity or the identity of the patterns existing in thesame image. Thus, the HEVC working committee is studying and planning aplurality of matching modes for improving compression performancesignificantly by fully exploring and utilizing the similar or identicalpatterns existing in computer screen images. The plurality of matchingmodes include intra block matching (also called intra block copy), microblock matching, fine division matching, string matching, micro blockstring matching, color palette-index matching, 2-dimensionalshape-preserving matching, quadtree matching and arbitrary shape andarea copy matching etc. In each of these matching modes, a matchingrelationship is represented with several basic matching relationshipparameters which may be, for example, matching position and matchingsize. Herein matching position represents a position of matchingreference pixel values matched with the pixel values in current coding(or decoding) (collectively referred to as currently matched pixelvalues) in a reference pixel value set composed of reconstructed pixels,and matching size represents the number of the currently matched pixelvalues. Obviously, the number of the currently matched pixel values isequal to that of matching reference pixel values.

Matching position is a relative position between matching referencepixel values and the currently matched pixel values. In an image, theposition of matching reference pixel values can be represented bytwo-dimensional coordinates or a linear address, and the position of thecurrently matched pixel values can also be represented bytwo-dimensional coordinates or a linear address. Thus, a matchingposition can be represented by the differences between thetwo-dimensional coordinates of a matching reference pixel values and thetwo-dimensional coordinates of the currently matched pixel values or thedifference between the linear address of matching reference pixel valuesand the linear address of the currently matched pixel values, thedifference is also called “displacement vector”. In the case of the useof two-dimensional coordinates, a matching position, that is, adisplacement vector, is represented by two matching relationshipparameters, that is, two vector components, for example, a horizontalvector component and a vertical component. In the case of the use of alinear address, a matching position, that is, a displacement vector, isrepresented by a matching relationship parameter, that is, thedifference of two linear addresses, which is generally called “matchingdistance”.

Matching size represents the total number of the currently matched pixelvalues having the same matching position. Because the number of thecurrently matched pixel values is equal to that of matching referencepixel values, matching size also represents the total number of thematching reference pixel values with the same matching position. In somematching modes, matching size is a matching relationship parameter, forexample, the length of a matched string or the numbers of a plurality ofpreset matching shapes and sizes (e.g. 4×4 square blocks with pixelvalues, 4×8 blocks with pixel values, 8×8 square blocks with pixelvalues and 16×16 square blocks with pixel values). In some matchingmodes, matching size may be several matching relationship parameters,for example, two matching relationship parameters, that is, heights andwidths of a matching rectangle, or three matching relationshipparameters, that is, height of a matching right trapezoid and widths ofthe upper side and the lower side of the matching right trapezoid, orthree matching relationship parameters equivalent to the foregoing threeparameters, I matching relationship parameters representing lengths of Ihorizontal lines constituting a matching region.

The value range of a matching relationship parameter is a preset finiteelement set in which numerals are arranged in a certain order, commonly,a set of integers arranged in ascending order. For example, the valuerange of a matching relationship parameter representing the differencebetween linear addresses of matching positions (usually called amatching distance) is from 1 to D (D=1048576), where D represents themaximum allowable matching distance. For another example, the valuerange of a matching relationship parameter representing the length of amatched string is from 1 to L (L=12288), where L represents the maximumallowable length of a matched string.

Two or three or more matching relationship parameters may also becombined into one matching relationship parameter by conducting someoperations. The matching relationship parameter resulting from thecombination has a wider value range.

Data compression must be performed on matching relationship parametersthrough entropy coding. The input of entropy coding is integers within apreset value range. Entropy coding is divided into two steps: 1)binarizing an input integer, that is, converting an integer into astring of bins, herein each bin is 0 or 1; and 2) performingcontext-based adaptive binary arithmetic coding on each bin.

The binarization methods used in related technologies all have a featurethat, a relatively smaller quantity of data generated from entropycoding is written into a compressed bitstream because a relativelysmaller integer is converted into a relatively shorter string of binsafter binarization, while a relatively bigger quantity of data generatedfrom entropy coding is written into a compressed bitstream because arelatively bigger integer is converted into a relatively longer stringof bins after being binarized.

Because of this feature of binarization methods, if there is an overalltrend that the larger an integer included in the value range of amatching relationship parameter is, the less the integer appears in thewhole coding process, then entropy coding will achieve a good datacompression performance. Contrarily, if the frequency of the appearanceof an integer included in the value range of a matching relationshipparameter gets higher and lower and repeatedly oscillates as the valueof the matching relationship parameter becomes larger, then the datacompression performance of entropy coding is impacted negatively.

In many cases, the frequency of the appearance of any integer in thevalue range of a matching relationship parameter in the whole codingprocess is not always reduced as the value of the integer increases, anappearance frequency p(A) of a certain integer A may be quite greaterthan an appearance frequency p(B) of another integer B which is muchsmaller than A, that is, A is much greater than B while p(A) is muchgreater than p(B), as a result, a feature that the frequency becomeshigher and lower and repeatedly oscillates as a value of an integerincreases, appears.

In existing technologies, directly applying entropy coding to matchingrelationship parameters would usually lead to the following problem thatone special integer value of a matching relationship parameter appearshighly frequently but is of a great value and thus a large number ofbitstream data will be generated by applying entropy coding to thisspecial integer value.

No effective solutions have been proposed to address the problemexisting in the conventional art which is caused by the directimplementation of entropy coding for a matching relationship parameter.

SUMMARY

The present document provides an image coding and decoding method andapparatus to at least address the problem existing in the conventionalart which is caused by the direct implementation of entropy coding for amatching relationship parameter.

In accordance with an aspect of the present document, an image codingapparatus is provided which includes the following modules: a module 1):a pixel preprocessing and matching coding module arranged to performpixel preprocessing and matching coding on pixel values of an inputvideo image to generate and output one or more matching relationshipparameters and other matching coding result except the one or morematching relationship parameters; a module 2): a mapping module arrangedto perform one-to-one mapping on a value range of the matchingrelationship parameters, herein input of the mapping is the matchingrelationship parameters output by the module 1), and output of themapping is the mapped matching relationship parameters; a module 3): acoding and reconstructing module arranged to perform coding andreconstruction operations on the input video image, the matchingrelationship parameters and variables; a module 4): a temporary storagemodule arranged to temporarily store pixel values in a reconstructedreference pixel value set; and a module 5): an entropy coding modulearranged to perform entropy coding operations on all coding results thatneed to be output to a compressed bitstream and include the mappedmatching relationship parameters and other coding result, and output aresult of the entropy coding, herein the result of the entropy codingincludes compressed data of the matching relationship parameters and acompressed bitstream of the other coding result.

In an exemplary embodiment, the value range is divided into Ksubordinate value ranges, and accordingly, the mapping is also dividedinto mappings in the K subordinate value ranges.

In an exemplary embodiment, the value range is divided into L groups ofsubordinate value ranges, each subordinate value range in each group ofsubordinate value ranges includes equal finite elements, accordingly,the mapping is also divided into L groups of mappings; through eachgroup of mappings, a complete subordinate value range in a group ofsubordinate value ranges is mapped into a complete subordinate valuerange in the same group while keeping a sequence of all elements in thesubordinate value range unchanged, herein L is a natural number.

In an exemplary embodiment, one of the mappings in the value range orthe subordinate value range is consisted of a plurality of partialmappings that are implemented successively.

In an exemplary embodiment, mapping relationships for one of themappings or partial mappings in the value range or the subordinate valuerange are represented in one of the following ways: the mappingrelationships are all represented by one computation expression or agroup of computation expressions; the mapping relationships are allrepresented by a list; a part of the mapping relationships arerepresented by one computation expression or a group of computationexpressions while others are represented by a list.

In an exemplary embodiment, a mapping relationship for one of themappings or partial mappings in the value range or the subordinate valuerange changes as status and/or parameters of current coding change.

In an exemplary embodiment, a mapping relationship for one of themappings or partial mappings in the value range or the subordinate valuerange changes as a width of a current coding block changes.

In an exemplary embodiment, one of the matching relationship parametersis a matching distance, and the width W of the current coding block hasfour values: 64, 32, 16 and 8, and accordingly, the mapping has fourmapping relationships.

In an exemplary embodiment, the apparatus further includes: a real-timestatistic module arranged to make real-time statistics oncharacteristics of various numerical values in the value range of thematching relationship parameters and dynamically adjust a mappingrelationship of the mapping or partial mapping according to a result ofthe real-time statistics on various numerical values of the matchingrelationship parameters.

In accordance with another aspect of the present document, an imagedecoding apparatus is also provided which includes the followingmodules: a module 1): an entropy decoding module arranged to performentropy decoding on an input compressed bitstream including compresseddata of matching relationship parameters and other coding result exceptthe compressed data of the matching relationship parameters, and parsevarious data obtained from the entropy decoding; a module 2): an inversemapping module arranged to perform one-to-one inverse mapping on a valuerange of mapped matching relationship parameters, herein through theinverse mapping, matching relationship parameters before the mapping isrestored and output; a module 3): a matching decoding module arranged toperform matching decoding operations according to the matchingrelationship parameters; a module 4): a decoding and reconstructingmodule arranged to perform decoding and reconstruction operations onvarious parameters and variables in a matching region in currentdecoding or a decoding block in current decoding; and a module 5): atemporary storage module arranged to temporarily store pixel values in areconstructed reference pixel value set.

In an exemplary embodiment, the matching region is a matching string ora matching block.

In an exemplary embodiment, the value range is divided into Ksubordinate value ranges, and accordingly, the inverse mapping is alsodivided into inverse mappings in the K subordinate value ranges.

In an exemplary embodiment, the value range is divided into L groups ofsubordinate value ranges, each subordinate value range in each group ofsubordinate value range includes equal finite elements, accordingly, theinverse mapping is also divided into L groups of inverse mappings;through a group of inverse mappings, a complete subordinate value rangein a group of subordinate value ranges is inversely mapped into acomplete subordinate value range in the same group while keeping asequence of all elements in the subordinate value range unchanged,herein L is a natural number.

In an exemplary embodiment, one of the mappings or the inverse mappingsin the value range or the subordinate value range is consisted of aplurality of partial mappings or partial inverse mappings that areimplemented successively.

In an exemplary embodiment, inverse mapping relationships for one of theinverse mappings or partial inverse mappings in the value range or thesubordinate value range are represented in one of the following ways:the inverse mapping relationships are all represented by one computationexpression or a group of computation expressions; the inverse mappingrelationships are all represented by a list; a part of the inversemapping relationships are represented by one computation expression or agroup of computation expressions while others are represented by a list.

In an exemplary embodiment, an inverse mapping relationship for one ofthe inverse mappings or partial inverse mappings in the value range orthe subordinate value range changes as status and/or parameters ofcurrent coding change.

In an exemplary embodiment, an inverse mapping relationship for one ofthe inverse mappings or partial inverse mappings in the value range orthe subordinate value range changes as a width of the decoding blockchanges.

In an exemplary embodiment, one of the matching relationship parametersis a matching distance, the width W of the decoding block has fourvalues: 64, 32, 16 and 8, and accordingly, the inverse mapping has fourinverse mapping relationships.

In an exemplary embodiment, the apparatus further includes: a real-timestatistic module arranged to make real-time statistics oncharacteristics of various numerical values in the value range of thematching relationship parameters and dynamically adjust an inversemapping relationship of the inverse mapping or partial inverse mappingaccording to a result of the real-time statistics on various numericalvalues of the matching relationship parameters.

In accordance with an aspect of the present document, an image codingmethod is provided which includes: performing pixel preprocessing andmatching coding on pixel values of an input video image to generate andoutput one or more matching relationship parameters; performingone-to-one mapping on a value range of the matching relationshipparameters and outputting the mapped matching relationship parameters;performing coding and reconstruction operations on the input videoimage, the matching relationship parameters and variables; temporarilystoring pixel values in a reconstructed reference pixel value set; andperforming entropy coding on the mapped matching relationship parametersand outputting a result of the entropy coding.

In accordance with another aspect of the present document, an imagedecoding method is also provided which includes: performing entropydecoding on an input compressed bitstream including compressed data ofmatching relationship parameters and other parameters except thecompressed data of the matching relationship parameters; performingone-to-one inverse mapping on a value range of mapped matchingrelationship parameters to restore and output a matching relationshipparameters before the mapping; performing matching decoding according tothe matching relationship parameters; performing decoding andreconstruction operations on various parameters and variables in amatching region in current decoding or a decoding block in currentdecoding; and temporarily storing pixel values in a reconstructedreference pixel value set.

In accordance with an aspect of the present document, an image codingmethod is provided which includes: performing matching coding on pixelsof an input video image to obtain one or more matching relationshipparameters, herein the matching relationship parameters are parametersused in a process of constructing predicted values and/or reconstructedvalues of the pixels in the input video image; mapping the matchingrelationship parameters to obtain mapped values of the matchingrelationship parameters; and performing entropy coding on the mappedvalue of the matching relationship parameters.

In an exemplary embodiment, mapping the matching relationship parametersincludes: converting, according to existing matching relationshipparameters, matching relationship parameters to be matched, and takingvalues obtained after the conversion as the mapped values of therelationship parameters to be matched; and/or assembling and/orrearranging matching relationship parameters of a same type into amatching relationship parameter group according to a specific rule,mapping the matching relationship parameter group, and taking thematching relationship parameter group obtained after the mapping as themapped values of the matching relationship parameters.

In an exemplary embodiment, the specific rule includes at least one ofthe following rules: a preset rule; and an operation which is setaccording to a value of the existing matching relationship parameter forassembling and/or rearranging a plurality of relationship parameters tobe matched.

In an exemplary embodiment, mapping the matching relationship parametergroup includes: taking values of the matching relationship parameters inthe matching relationship parameter group as an output of the mapping;and/or taking values obtained after converting the values of thematching relationship parameters in the matching relationship parametergroup as an output of the mapping.

In accordance with another aspect of the present document, an imagedecoding method is provided which includes: performing entropy decodingon a received bitstream to obtain values of fields for indicatingmatching relationship parameters, herein the matching relationshipparameters are parameters used in a process of constructing predictedvalues and/or reconstructed values of the pixels in a video image to bedecoded; mapping the values of the fields to obtain mapped matchingrelationship parameters; and constructing the predicted values and/orthe reconstructed values of the pixels in the video image to be decodedaccording to the mapped matching relationship parameters.

In an exemplary embodiment, mapping the values of the fields to obtainmapped matching relationship parameters includes: converting, accordingto the obtained matching relationship parameters, the values of thefields to be processed, and taking values obtained after the conversionas the mapped matching relationship parameters; and/or assembling and/orrearranging the values of the fields to be processed of a same type intoan array according to a specific rule, and processing the array as themapped matching relationship parameters.

In an exemplary embodiment, the specific rule includes at least one ofthe following rules: a preset rule; and an operation which is setaccording to the obtained values of the fields for the assembly and/orrearrangement the values of the fields to be processed.

In an exemplary embodiment, processing the array includes: taking valuesof the fields to be processed in the array as output values afterprocessing; and/or taking values obtained after converting the values ofthe fields to be processed in the array as output values afterprocessing.

In accordance with an aspect of the present document, an image codingapparatus is provided which includes: a matching coding module arrangedto perform matching coding on pixels of an input video image to obtainone or more matching relationship parameters, herein the matchingrelationship parameters are parameters used in a process of constructingpredicted values and/or reconstructed values of the pixels in the inputvideo image; a mapping module arranged to map the matching relationshipparameters to obtain mapped values of the matching relationshipparameters; and an entropy coding module arranged to perform entropycoding on the mapped values of the matching relationship parameters.

In accordance with another aspect of the present document, an imagedecoding apparatus is also provided which includes: an entropy decodingmodule arranged to perform entropy decoding on a received bitstream toobtain values of fields for indicating matching relationship parameters,herein the matching relationship parameters are parameters used in aprocess of constructing predicted values and/or reconstructed values ofpixels in a video image to be decoded; a mapping module arranged to mapthe values of the fields to obtain mapped matching relationshipparameters; and a construction module arranged to construct thepredicted values and/or the reconstructed values of the pixels in thevideo image to be decoded according to the mapped matching relationshipparameters.

With the present document, by implementing matching coding for thepixels of an input video image, one or more matching relationshipparameters are obtained, herein the matching relationship parameters areparameters used in the process of constructing the predicted valuesand/or the reconstructed values of the pixels in the image, the matchingrelationship parameters are mapped to obtain the mapped values of thematching relationship parameters, and entropy coding is performed on themapped values of the matching relationship parameters, it is to addressthe problem existing in the conventional art which is caused by directlyperforming entropy coding on matching relationship parameters, thusachieving a good data compression performance through entropy coding.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings described herein which form a part of theapplication are provided for the further understanding of the presentdocument, and exemplary embodiments of the present document and thedescription of the exemplary embodiments serve to illustrate the presentdocument but are not to be construed as improper limitations to thepresent document. In the accompanying drawings:

FIG. 1 is a block diagram illustrating the structure of an image codingapparatus according to an embodiment of the present document;

FIG. 2 is a block diagram (1) illustrating the structure of an imagecoding apparatus according to an embodiment of the present document;

FIG. 3 is a flowchart illustrating an image coding method according toan embodiment of the present document;

FIG. 4 is a block diagram illustrating the structure of an imagedecoding apparatus according to an embodiment of the present document;

FIG. 5 is a block diagram (1) illustrating the structure of an imagedecoding apparatus according to an embodiment of the present document;

FIG. 6 is a flowchart illustrating an image decoding method according toan embodiment of the present document;

FIG. 7 is a flowchart (1) illustrating an image coding method accordingto an embodiment of the present document;

FIG. 8 is a block diagram (2) illustrating the structure of an imagecoding apparatus according to an embodiment of the present document;

FIG. 9 is a flowchart (1) illustrating an image decoding methodaccording to an embodiment of the present document;

FIG. 10 is a block diagram (2) illustrating the structure of an imagedecoding apparatus according to an embodiment of the present document;

FIG. 11 is a schematic diagram illustrating a bi-directional singlemapping in the value range of a matching relationship parameteraccording to an embodiment of the present document;

FIG. 12 is a schematic diagram illustrating the modules of a codingapparatus according to an embodiment of the present document; and

FIG. 13 is a schematic diagram illustrating the modules of a decodingapparatus according to an embodiment of the present document.

DETAILED DESCRIPTION

The present document will be described below in detail with reference toaccompanying drawings and in conjunction with specific embodiments. Itshould be noted that the embodiments of the present application and thefeatures thereof can be combined with each other in case of no conflict.

FIG. 1 is a block diagram illustrating the structure of an image codingapparatus according to an embodiment of the present document. As shownin FIG. 1, the image coding apparatus includes: a module 1): a pixelpreprocessing and matching coding module 22 arranged to perform pixelpreprocessing and matching coding on pixel values of an input videoimage to generate and output one or more matching relationshipparameters and other matching coding result except the one or morematching relationship parameters; a module 2): a mapping module 24arranged to perform one-to-one mapping on value ranges of the matchingrelationship parameters, herein input of the mapping is the matchingrelationship parameters output by the module 1), and output of themapping is the mapped matching relationship parameters; a module 3): acoding and reconstructing module 26 arranged to perform coding andreconstruction operations on the input video image, the matchingrelationship parameters and variables; a module 4): a temporary storagemodule 28 arranged to temporarily store pixel values in a reconstructedreference pixel value set; and a module 5): an entropy coding module 30arranged to perform entropy coding operations on all coding results thatneed to be output to compressed bitstream and include the mappedmatching relationship parameters and the other coding result, and outputa result of the entropy coding, herein the result of the entropy codingincludes compressed data of the matching relationship parameters and acompressed bitstream of the other coding result.

With the foregoing image coding apparatus, after mapping matchingrelationship parameters, the mapped matching relationship parameters arecoded, compared with the conventional art in which the directimplementation of entropy coding for matching relationship parametersleads to a problem that a great number of compressed bitstream data aregenerated after entropy coding is performed because a certain integer ofthe matching relationship parameters is large and appears highlyfrequently, the foregoing image coding apparatus solves the problemcaused by the direct implementation of entropy coding for matchingrelationship parameters in the existing technology and further achievesa good data compression performance through entropy coding.

In an alternative embodiment, the value range is divided into Ksubordinate value ranges, and accordingly, the mapping is also dividedinto mappings in the K subordinate value ranges.

In another alternative embodiment, the value range is divided into Lgroups of subordinate value ranges, each subordinate value range in eachgroup of subordinate value ranges includes equal finite elements,accordingly, the mapping is also divided into L groups of mappings;through a group of mappings, a complete subordinate value range in agroup of subordinate value ranges is mapped into a complete subordinatevalue range in the same group while keeping a sequence of all elementsin the subordinate value range unchanged, herein L is a natural number.

In an alternative embodiment, a mapping in the value range or thesubordinate value range is consisted of a plurality of partial mappingsthat are implemented successively.

The mapping relationships for one of the mappings or partial mappings inthe value range or the subordinate value range may be represented in aplurality of ways which will be exemplified below. In an alternativeembodiment, the mapping relationships are represented in one of thefollowing ways: the mapping relationships are all represented by onecomputation expression or a group of computation expressions; themapping relationships are all represented by a list; a part of themapping relationships are represented by one computation expression or agroup of computation expressions while the others are represented by alist.

In an alternative embodiment, a mapping relationship for one of themappings or partial mappings in the value range or the subordinate valuerange changes as status and/or parameters of current coding change.

In another alternative embodiment, a mapping relationship for one of themappings or partial mappings in the value range or the subordinate valuerange changes as a width of a current coding block changes.

There are a plurality of kinds of matching relationship parameters, inthe case where the matching relationship parameter is a matchingdistance, in an alternative embodiment, the width W of the currentcoding block has four values: 64, 32, 16 and 8, and accordingly, themapping has four mapping relationships.

FIG. 2 is a block diagram (1) illustrating the structure of an imagecoding apparatus according to an embodiment of the present document. Asshown in FIG. 2, the apparatus further includes: a real-time statisticmodule 32 arranged to make real-time statistics on characteristics ofvarious numerical values in the value range of the matching relationshipparameters and dynamically adjust a mapping relationship of the mappingor partial mapping according to a result of the real-time statistics onvarious numerical values of the matching relationship parameters.

In another embodiment, an image coding method is provided, FIG. 3 is aflowchart illustrating an image coding method according to an embodimentof the present document, and as shown in FIG. 3, the flow includes thefollowing steps.

In Step S302, pixel preprocessing and matching coding are performed onpixel values of an input video image to generate and output one or morematching relationship parameters.

In Step S304, one-to-one mapping is performed on the value range of thematching relationship parameters, and the mapped matching relationshipparameters are output.

In Step S306, coding and reconstruction operations are performed on theinput video image, the matching relationship parameters and variables.

In Step S308, the pixel values in a reconstructed reference pixel valueset are stored temporarily.

In Step S310, entropy coding is performed on the mapped matchingrelationship parameters to output a result of the entropy coding.

By executing the foregoing steps, after mapping matching relationshipparameters and coding the mapped matching relationship parameters,compared with the conventional art in which the direct implementation ofentropy coding for a matching relationship parameter leads to a problemthat a great number of compressed bitstream data are generated afterentropy coding is performed because a certain integer of the matchingrelationship parameter is very large and appears highly frequently, theforegoing image coding apparatus solves the problem caused by the directimplementation of entropy coding for matching relationship parameters inthe conventional art and achieves a good data compression performancethrough entropy coding.

FIG. 4 is a block diagram illustrating the structure of an imagedecoding apparatus according to an embodiment of the present document.As shown in FIG. 4, the apparatus includes the following modules: amodule 1): an entropy decoding module 42 arranged to perform entropydecoding on an input compressed bitstream including compressed data ofmatching relationship parameters and other coding result except thecompressed data of the matching relationship parameters, and parsevarious data obtained from the entropy decoding; a module 2): an inversemapping module 44 arranged to perform one-to-one inverse mapping on avalue range of mapped matching relationship parameters, herein throughthe inverse mapping, matching relationship parameters before the mappingare restored and output; a module 3): a matching decoding module 46arranged to perform matching decoding operations according to thematching relationship parameters; a module 4): a decoding andreconstructing module 48 arranged to perform decoding and reconstructionoperations on various parameters and variables in a matching region incurrent decoding or a decoding block in current decoding; and a module5): a temporary storage module 50 arranged to temporarily store pixelvalues in a reconstructed reference pixel value set.

By inversely mapping the value range of mapped matching relationshipparameters obtained from an entropy coding process to output matchingrelationship parameters before the mapping, the foregoing image decodingapparatus addresses the problem existing in the conventional art whichis caused by the direct implementation of entropy coding for matchingrelationship parameters and achieves a good data compression performancethrough entropy coding.

In an alternative embodiment, the matching region is a matching stringor a matching block.

In an alternative embodiment, the value range is divided into Ksubordinate value ranges, and accordingly, the inverse mapping is alsodivided into inverse mappings in the K subordinate value ranges.

In another alternative embodiment, the value range is divided into Lgroups of subordinate value ranges, each subordinate value range in eachgroup of subordinate value ranges includes equal finite elements,accordingly, the inverse mapping is also divided into L groups ofinverse mappings; through a group of inverse mappings, a completesubordinate value range in a group of subordinate value ranges isinversely mapped into a complete subordinate value range in the samegroup while keeping a sequence of all elements in the subordinate valuerange unchanged, herein L is a natural number.

In another alternative embodiment, one of the mappings or the inversemappings in the value range or the subordinate value range is consistedof a plurality of partial mappings or partial inverse mappings that areimplemented successively.

Alternatively, inverse mapping relationships for one of the inversemappings or partial inverse mappings in the value range or thesubordinate value range can be represented in a plurality of ways, andin an alternative embodiment, the inverse mapping relationships arerepresented in one of the following ways: the inverse mappingrelationships are all represented by one computation expression or agroup of computation expressions; the inverse mapping relationships areall represented by a list; a part of the inverse mapping relationshipsare represented by one computation expression or a group of computationexpressions while the others are represented by a list.

In an alternative embodiment, an inverse mapping relationship for one ofthe inverse mappings or partial inverse mappings in the value range orthe subordinate value range changes as status and/or parameters ofcurrent coding change.

In another alternative embodiment, an inverse mapping relationship forone of the inverse mappings or partial inverse mappings in the valuerange or the subordinate value range changes as a width of the decodingblock changes.

The matching relationship parameter may be various kinds of information,in the case where the matching relationship parameter is a matchingdistance, in an alternative embodiment, the width W of the decodingblock has four values: 64, 32, 16 and 8, and accordingly, the inversemapping has four inverse mapping relationships.

FIG. 5 is a block diagram (1) illustrating the structure of an imagedecoding apparatus according to an embodiment of the present document.As shown in FIG. 5, the apparatus further includes: a real-timestatistic module 52 arranged to make real-time statistics oncharacteristics of various numerical values in the value range of thematching relationship parameters and dynamically adjust an inversemapping relationship of the inverse mapping or partial inverse mappingaccording to a result of the real-time statistics on various numericalvalues of the matching relationship parameters.

In another embodiment, an image coding method is provided, FIG. 6 is aflowchart illustrating an image decoding method according to anembodiment of the present document, and as shown in FIG. 6, the flowincludes the following steps.

In Step S602, entropy decoding is performed on an input compressedbitstream including compressed data of matching relationship parametersand other parameters except the compressed data of the matchingrelationship parameters.

In Step S604, a one-to-one inverse mapping is performed on a value rangeof mapped matching relationship parameters obtained from entropydecoding to restore and output matching relationship parameters beforethe mapping.

In Step S606, matching decoding is performed according to the matchingrelationship parameters.

In Step S608, decoding and reconstruction operations are performed onvarious parameters and variables in a matching region in currentdecoding or a decoding block in current decoding.

In Step S610, pixel values in a reconstructed reference pixel value setare stored temporarily.

By executing the foregoing steps, it is to inversely map the value rangeof a mapped matching relationship parameter obtained from an entropycoding process, to output a matching relationship parameter before themapping, it is to address the problem existing in the conventional artwhich is caused by the direct implementation of entropy coding formatching relationship parameters and achieve a good data compressionperformance through entropy coding.

In another embodiment, an image coding method is provided, FIG. 7 is aflowchart (1) illustrating an image coding method according to anembodiment of the present document. As shown in FIG. 7, the flowincludes the following steps.

In Step S702, matching coding is performed on pixels of an input videoimage to obtain one or more matching relationship parameters, herein thematching relationship parameters are parameters used in a process ofconstructing predicted values and/or reconstructed values of the pixelsin the input video image.

In Step S704, the matching relationship parameters are mapped to obtaina mapped value of the matching relationship parameters.

In Step S706, entropy coding is performed on the mapped values of thematching relationship parameters.

By the foregoing steps of mapping matching relationship parameters andcoding the mapped matching relationship parameters, compared with theconventional art in which the direct implementation of coding for amatching relationship parameter leads to a problem that a great numberof compressed bitstream data are generated after entropy coding isperformed because a certain integer of the matching relationshipparameter is very large and appears highly frequently, it is to solvethe problem caused by the direct implementation of entropy coding formatching relationship parameters in the conventional art and achieve agood data compression performance through entropy coding.

In an alternative embodiment, the frequency of the mapped value of amatching relationship parameter reduces as the mapped value of thematching relationship parameter increases, herein the frequencyindicates that the greater the mapped value is, the lower theprobability of the actual appearance of the mapped value is, that is,the less the mapped value appears.

In an alternative embodiment, mapping is performed on the matchingrelationship parameters in Step S704, it is to convert, according toexisting matching relationship parameters, relationship parameters to bematched, and take values obtained after converting as the mapped valuesof the relationship parameters to be matched, herein the mappingoperation may be appreciated as a direct ‘copy’ operation, that is, noprocessing is performed on the input data. And/or, it is to assemblyand/or rearrange matching relationship parameters of the same type intoa matching relationship parameter group according to a specific rule,map the matching relationship parameter group, and take the matchingrelationship parameter group obtained from the mapping as the mappedvalues of the matching relationship parameters. In this way, the mappingof a matching relationship parameters is realized.

The above specific rule may include a plurality of kinds of specificrules which will be exemplified below. In an alternative embodiment, thespecific rule may be a preset rule or an operation which is setaccording to the values of the existing matching relationship parametersfor assembling and/or rearranging a plurality of relationship parametersto be matched.

The foregoing matching relationship parameter group can be mapped byusing a plurality of methods which will be exemplified below. In analternative embodiment, the processing method can be taking the valuesof the matching relationship parameters in the matching relationshipparameter group as the output of the mapping, or taking the values ofthe matching relationship parameters in the matching relationshipparameter group obtained from the conversion as the output of themapping.

An image coding apparatus is also provided in the embodiment to realizethe foregoing embodiments and preferred implementations, and what hasbeen described above is not described here repeatedly. The term‘module’, as used hereinafter, is the combination of software and/orhardware for realizing predetermined functions. Although the apparatusesdescribed in the following embodiments are implemented as softwarepreferably, the implementation of the apparatuses as hardware orcombination of software and hardware may also be conceived.

FIG. 8 is a block diagram (2) illustrating the structure of an imagecoding apparatus according to an embodiment of the present document. Asshown in FIG. 8, the apparatus includes: a matching coding module 82arranged to perform matching coding on pixels of an input video image toobtain one or more matching relationship parameters, herein the matchingrelationship parameters are parameters used in a process of constructingpredicted values and/or reconstructed values of the pixels in the inputvideo image; a mapping module 84 arranged to map the matchingrelationship parameters to obtain mapped values of the matchingrelationship parameters; and an entropy coding module 86 arranged toperform entropy coding on the mapped values of the matching relationshipparameters.

In another embodiment, an image decoding method is provided, FIG. 9 is aflowchart (1) illustrating an image decoding method according to anembodiment of the present document. As shown in FIG. 9, the flowincludes the following steps.

In Step S902, entropy decoding is performed on a received bitstream toobtain values of fields for indicating matching relationship parameters,herein the matching relationship parameters are parameters used in aprocess of constructing predicted values and/or reconstructed values ofthe pixels in a video image to be decoded.

In Step S904, the values of the fields are mapped to obtain mappedmatching relationship parameters.

In Step S906, the predicted values and/or the reconstructed values ofthe pixels in the video image to be decoded are constructed according tothe mapped matching relationship parameters.

By the foregoing steps of inversely mapping the value range of a mappedmatching relationship parameters obtained from an entropy coding processand output matching relationship parameters before the mapping, it is toaddress the problem existing in the conventional art which is caused bythe direct implementation of entropy coding for matching relationshipparameters and achieve a good data compression performance throughentropy coding.

In an alternative embodiment, the frequency of the mapped value of amatching relationship parameter reduces as the mapped value of thematching relationship parameter increases, herein the frequencyindicates that the greater the mapped value is, the less the probabilityof the actual appearance of the mapped value is, that is, the less themapped value appears.

In an alternative embodiment, mapping is performed on the values of thefields in Step S904 to obtain mapped matching relationship parameters,according to the obtained matching relationship parameters, convert thevalues of the fields, and take the values obtained after conversion asthe mapped matching relationship parameters. In another alternativeembodiment, the fields to be processed of the same type are assembledand/or rearranged into an array according to a specific rule, and thenthe array is processed to be used as the mapped matching relationshipparameters.

In an alternative embodiment, the specific rule includes at least one ofthe following rules: a preset rule; and an operation which is setaccording to the obtained values of the fields for assembling and/orrearranging the values of the field to be processed.

Alternatively, in an alternative embodiment, the above mentioned arrayis processed using a method of taking the values of the fields to beprocessed in the array as output values after the processing or a methodof converting the values of the fields to be processed in the array andtaking the values obtained from the conversion as output values afterthe processing.

An image decoding apparatus is also provided in the embodiment torealize the foregoing embodiments and preferred implementations, andwhat has been described above is not described here repeatedly. The term‘module’, as used hereinafter, is the combination of software and/orhardware for realizing predetermined functions. Although the apparatusesdescribed in the following embodiments are preferably implemented assoftware, the implementation of the apparatuses as hardware orcombination of software and hardware may also be conceived.

FIG. 10 is a block diagram (2) illustrating the structure of an imagedecoding apparatus according to an embodiment of the present document.As shown in FIG. 10, the apparatus includes: an entropy decoding module102 arranged to perform entropy decoding on a received bitstream toobtain values of fields for indicating matching relationship parameters,herein the matching relationship parameters are parameters used in aprocess of constructing predicted values and/or reconstructed values ofpixels in an image to be decoded; a mapping module 104 arranged to mapthe values of the fields to obtain mapped matching relationshipparameters; and a construction module 106 arranged to construct thepredicted values and/or the reconstructed values of the pixels in theimage to be decoded according to the mapped matching relationshipparameters.

The foregoing problem existing in the conventional art will be describedbelow with reference to an exemplary alternative embodiment, and theforegoing alternative embodiments and the alternative implementationsthereof are combined in the alternative embodiment described below.

The major technical feature of the alternative embodiment lies in thatbi-directional single mapping (referred to as a bijection for short) isperformed on the value range of a matching relationship parameter beforeentropy coding is implemented for the matching relationship parameter tomap a value with a relatively high frequency in the value range into arelatively small value and a value with a relatively low frequency inthe value range into a relatively large value. Bijection is also calledone-to-one surjection. A bijection has an inverse mapping which is alsoa one-to-one surjection.

FIG. 11 is a schematic diagram illustrating a bi-directional singlemapping in the value range of a matching relationship parameteraccording to an embodiment of the present document, and as shown in FIG.11, the value range of a certain matching relationship parameter is aninteger interval from 1 to 12288, represented as [1,12288]. The featureof the frequency of the matching relationship parameter is that thefrequency for multiples of 4 (that is, 4, 8, 12, . . . , 6144, . . . ,12288) is much higher than that of multiples of integers which are not4. Multiples of 4 are mapped to integers from 1 to 3072, while integerswhich are not 4 are mapped to integers from 3073 to 12288, so that thefrequency of the mapped matching relationship parameter presents anoverall trend that the higher the value of the mapped matchingrelationship parameter, the lower the frequency of the mapped matchingrelationship parameter is, thus significantly improving the compressionefficiency of the subsequent entropy coding. The mapping formula shownin FIG. 11 is described below:

4k is mapped to k, in which k=1, 2, 3, 4, . . . 3072;

4k+1 is mapped to 3072+3k+1, in which k=0, 1, 2, 3, . . . 3071;

4k+2 is mapped to 3072+3k+2, in which k=0, 1, 2, 3, . . . 3071; and

4k+3 is mapped to 3072+3k+3, in which k=0, 1, 2, 3, . . . 3071.

The mapping is a self-bijection ranging from the integer interval [1,12288] to the integer interval [1, 12288], and the inverse mappingformula of the mapping is described below:

k is mapped to 4k, in which k=1, 2, 3, 4, . . . 3072;

3072+3k+1 is mapped to 4k+1, in which k=0, 1, 2, 3, . . . 3071;

3072+3k+2 is mapped to 4k+2, in which k=0, 1, 2, 3, . . . 3071; and

3072+3k+3 is mapped to 4k+3, in which k=0, 1, 2, 3, . . . 3071.

The inverse mapping is also a self-bijection ranging from the integerinterval [1, 12288] to the integer interval [1, 12288].

The most basic specific technical feature of the coding apparatusprovided in an alternative embodiment of the present document lies inthat mapping is performed on the value range of matching relationshipparameters generated from matching coding first, thus there is anoverall trend that the frequency values of the mapped matchingrelationship parameters reduces as the values of the mapped matchingrelationship parameters increases, and then entropy coding is performedon the mapped matching relationship parameters.

The most basic specific technical feature of the decoding apparatusprovided in an alternative embodiment of the present document lies inthat inverse mapping is performed on the value range of matchingrelationship parameters obtained from entropy decoding first (actually,mapped matching relationship parameters) to obtain real matchingrelationship parameters, and then matching decoding is conducted usingthe matching relationship parameters.

FIG. 12 is a schematic diagram illustrating the modules of a codingapparatus according to an embodiment of the present document; and asshown in FIG. 12, the whole coding apparatus is consisted of thefollowing modules.

1) A pixel preprocessing and matching coding module, arranged to performpixel preprocessing and matching coding on pixel values of an inputvideo image to generate and output one or more matching relationshipparameters (marked as a matching relationship parameter 1, a matchingrelationship parameter 2 . . . a matching relationship parameter Jrespectively) and other matching coding result. Examples of the pixelpreprocessing include: sample quantization, color quantization,color-based pixel clustering and the representation of the color of aninput original pixel with a color palette and an index; examples of thematching coding include: block matching, micro block matching, microblock string matching, fine division matching, string matching, colorpalette-index matching, 2-dimensional shape-preserving matching,quadtree matching and arbitrary shape and area copy matching; examplesof the matching relationship parameters include: matching position,displacement vector, a component of a displacement vector, matchingdistance, matching size, matching length, a height of a matchingrectangle, a width of a matching rectangle, a group of parametersdefining a specific matching region, and the numbers of a plurality ofpreset matching shapes and sizes, herein the value range of a matchingrelationship parameter is a preset finite element set in which numeralsare arranged in a certain order, for example, a finite element subsetconsisting of integers arranged in ascending order; and examples of theother matching coding result include: matching residual and unmatchedpixel values.

2) A mapping module for a value range of a matching relationshipparameter, arranged to perform bi-directional single mapping on a valuerange of the matching relationship parameters, herein input of themapping is the matching relationship parameters output by the module 1),through the mapping, mapped matching relationship parameters aregenerated and output, and the purpose of the mapping is to map a valueof relatively high frequency in the value range into a relatively smallvalue, and a value of relatively low frequency in the value range into arelatively large value; bi-directional single mapping, that is, aone-to-one surjection, is referred to as bijection for short, abijection has an inverse mapping which is also a one-to-one surjection;each matching relationship parameter has its own mapping; and mappingmodules for a matching relationship parameter 1, a matching relationshipparameter 2 . . . a matching relationship parameter J are marked as amapping module 1 for a value range, a mapping module 2 for a value range. . . and a mapping module J for a value range, respectively; themappings of some matching relationship parameters may be identitymappings (each value in the value range is mapped to the value itself),however, at least one mapping of one matching relationship parameter isnot an identity mapping; the mapping relationship of the mapping (thatis, the relationship between the input of the mapping and the output ofthe mapping, or which input value is mapped to which output value) maybe a preset static mapping relationship, or the mapping relationship maybe adjusted dynamically according to the real-time statisticcharacteristic of various values of the input matching relationshipparameters (e.g. the frequency at which the value appears till thecurrent moment).

3) A coding and reconstructing module for other matching modes andvarious common technologies, arranged to perform coding andreconstruction operations of other matching modes and various commontechnologies, for example, intra prediction, inter prediction,conversion, quantization, inverse conversion, inverse quantization,offset corresponding to prediction residual and matching residual (thatis, inverse operation of residual calculation operation), DPCM,first-order difference and higher-order difference, mapping, run, index,deblocking filter and sample adaptive offset, on the input video image,various parameters and variables. Other matching modes refer to matchingmodes different from those adopted in the module 1), the input of thepresent module is the output from the module 1), reference pixel valuesand the original pixel values of the input video image, and the outputfrom the present module is reconstructed pixel values and other codingresult; the reconstructed pixel values are placed in a temporary storagemodule for reconstructed reference pixel values as reference pixelvalues needed for the subsequent matching coding operations and thecoding and reconstruction operations of other matching modes and variouscommon technologies.

4) A temporary storage module for reconstructed reference pixel values,arranged to temporarily store pixel values in a reconstructed referencepixel value set, that is, the reconstructed pixel values ended at astart of the CU in current decoding or the matching region (or amatching string or a matching block) in current decoding during a codingprocess, used as reference pixel values for the current and thesubsequent matching coding, and as reference pixel values needed forperforming coding and reconstruction operations of other matching modesand various common technologies on current and subsequent CUs.

5) An entropy coding module, arranged to implement entropy coding forall the coding results that need to be output to a compressed bitstream,herein the coding results include the mapped matching relationshipparameters and the other coding result, and the result of the entropycoding, that is, a compressed bitstream including the compressed data ofthe matching relationship parameters and the other coding result, isalso the final output of the coding apparatus.

FIG. 13 is a schematic diagram illustrating the modules of a decodingapparatus according to an embodiment of the present document. As shownin FIG. 13, the whole decoding apparatus is consisted of the followingmodules.

1) An entropy decoding module, arranged to perform entropy decoding onan input compressed bitstream including compressed data of a matchingrelationship parameters and other coding result to parse the meanings ofthe various data obtained from the entropy decoding; map one or moremapped matching relationship parameters (marked as a mapped matchingrelationship parameter 1, a mapped matching relationship parameter 2 . .. a mapped matching relationship parameter J respectively) obtainedafter the parsing process to an inverse mapping module for a valuerange; output other data and other matching coding results such asmatching residual and unmatched pixel values obtained from the parsingprocess to a decoding and reconstructing module for other matching modesand various common technologies, herein the value range of the mappedmatching relationship parameters is a preset finite element set in whichnumerals are arranged in a certain order, for example, a finite elementset in which integers are arranged in ascending order.

2) An inverse mapping module for a value range of matching relationshipparameters, arranged to perform the inverse mapping of a bi-directionalsingle mapping on the value range of mapped matching relationshipparameters, herein the input of the inverse mapping is the mappedmatching relationship parameters parsed and output from the module 1),through the inverse mapping, the matching relationship parametersexisting prior to the mapping (that is, the matching relationshipparameters on which the mapping is not implemented in the codingapparatus) are restored and output; each matching relationship parameterhas its own inverse mapping; and inverse mapping modules for a matchingrelationship parameter 1, a matching relationship parameter 2 . . . amatching relationship parameter J are marked as an inverse mappingmodule 1 for a value range, an inverse mapping module 2 for a valuerange . . . an inverse mapping module J for a value range, respectively;the inverse mappings of some matching relationship parameters may beidentity mappings (each value in the value range is mapped to the valueitself), however, at least one inverse mapping of one matchingrelationship parameter may not be identity mapping; the inverse mappingrelationship of the inverse mapping (that is, the relationship betweenthe input of the inverse mapping and the output of the inverse mapping,or which input value is inversely mapped to which output value) may be apreset static inverse mapping relationship, or the inverse mappingrelationship may be adjusted dynamically according to the real-timestatistic feature of various values of the matching relationshipparameters (e.g. the frequency at which the value appears till thecurrent moment); examples of the matching relationship parametersinclude: matching position, displacement vector, a component of adisplacement vector, matching distance, matching size, matching length,a height of a matching rectangle, a width of a matching rectangle, agroup of parameters defining a specific matching region, and the numbersof a plurality of preset matching shapes and sizes.

3) A matching decoding module arranged to perform matching decodingoperations on the matching relationship parameters, herein the input ofthe module is the matching relationship parameters output from themodule 2; and examples of the matching decoding include: block matching,micro block matching, micro block string matching, fine divisionmatching, string matching, color palette-index matching, 2-dimensionalshape-preserving matching, quadtree matching and arbitrary shape andarea copy matching; in the matching decoding operations, firstly, theposition of a matching reference pixel value in the temporary module forreconstructed reference pixel values and the shape and the size of amatching region consisting of matching reference pixel values (thematching region may also be a matching string or matching block) aredetermined, then the matching reference pixel values in the matchingregion of the shape and the size are copied from the position, and thematching reference pixel values are copied to the position of thecurrently matched pixel value in current decoding to reconstruct thecurrently matched pixel values, herein the output of the present moduleis all the currently matched pixel values reconstructed.

4) A decoding and reconstructing module for other matching modes andvarious common technologies, arranged to perform decoding andreconstruction operations of other matching modes and various commontechnologies, for example, intra prediction, inter prediction, inverseconversion, inverse conversion, offset corresponding to predictionresidual and matching residual (that is, the inverse operation ofresidual calculation operation), DPCM, first-order difference andhigher-order difference, mapping, run, index, deblocking filter, andsample adaptive offset, on various parameters and variables of thematching region (the matching region may also be a matching string or amatching block) in current decoding or the CU in current decoding; theother matching modes refer to matching modes different from thoseadopted in the module 3), and the output from the module isreconstructed pixel values (including completely reconstructed pixelvalues and partially reconstructed pixel values that are reconstructedin different degrees); the reconstructed pixel values are placed in atemporary storage module for reconstructed reference pixel values asreference pixel values needed for the subsequent matching codingoperations, the decoding and reconstruction operations in other matchingmodes and various common technologies; and the completely reconstructedpixel values are also the final output of the decoding apparatus.

5) A temporary storage module for reconstructed reference pixel values,arranged to temporarily store the pixel values in a reconstructedreference pixel value set, that is, the reconstructed pixel values endedat a start of the CU in current decoding or the matching region (thematching region may also a matching string or a matching block) incurrent decoding during a coding process, used as reference pixel valuesfor the current and the subsequent matching decoding, and as referencepixel values needed for performing the decoding and reconstructionoperation in other matching modes and various common technologies on thecurrent and the subsequent CUs.

Alternative embodiments of the present document are applicable to codingand decoding an image or a CU in a packed format. Alternativeembodiments of the present document are also applicable to coding anddecoding an image or a CU in a component planar format. Alternativeembodiments of the present document are applicable to lossless matchingcoding and decoding. Embodiments of the present document are alsoapplicable to lossy matching coding and decoding. Embodiments of thepresent document are applicable to lossless coding and decoding.Embodiments of the present document are also applicable to lossy codingand decoding. Alternative embodiments of the present document are alsoapplicable to coding and decoding using a plurality of matching modessimultaneously (for example, using three following matching modes: blockmatching, arbitrary shape region copy matching and color palette-indexmatching simultaneously, or three following matching modes: blockmatching, palette-index matching and string matching simultaneously).

The accompanying drawings provided above explicate, by way ofillustration only, the basic concept and operations of embodiments ofthe present document only these components which are directly related toembodiments of the present document are shown in the accompanyingdrawings, and these components are not drawn according to the number,the shapes or the sizes of the components in practical implementation,and the forms, the number and the scales of various components inpractical implementation can be changed optionally, moreover, the layoutof the components may be more complicated.

More implementation details and variations of alternative embodiments ofthe present document are described below.

Embodiment 1 for the Mapping of the Value Range of Matching RelationshipParameters

The value range is divided into K (generally, 1<K<20) subordinate valueranges, and accordingly, the mapping and/or the inverse mapping isdivided into corresponding mapping or inverse mapping in the Ksubordinate value ranges.

Embodiment 2 for the Mapping of the Value Range of a MatchingRelationship Parameters

The value range is divided into L (generally, 1<L<40) groups ofsubordinate value ranges, each subordinate value range in each group ofsubordinate value ranges includes equal finite elements, andaccordingly, the mapping or the inverse mapping is divided into L groupsof mappings and/or inverse mappings. Through each group of mappingsand/or inverse mappings, a complete subordinate value range in a groupof subordinate value ranges is mapped or inversely mapped into acomplete subordinate value range (which can be the same subordinatevalue range or another one) in the same group, while keeping a order ofall elements in the subordinate value range unchanged, that is, if anelement A is located in front of an element B, after the mapping, theelement A is still located in front of the element B, or after theinverse mapping, the element A is still located in front of the elementB, or vice versa.

Embodiment 3 for the Mapping of the Value Range of Matching RelationshipParameters

One of the mappings or the inverse mappings in the value range and/orthe subordinate value range are consisted of a plurality of (generally,not less than 4) partial mappings and/or partial inverse mappings thatare implemented successively.

Embodiment 4 for the Mapping of the Value Range of Matching RelationshipParameters

The mapping/inverse mapping relationships for one of themappings/inverse mappings (or the partial mappings/inverse mappings) inthe value range or the subordinate value range are represented in one ofthe following ways: the mapping relationships and/or the inverse mappingrelationships are all represented by one computation expression or agroup of computation expressions; or the mapping relationships and/orthe inverse mapping relationships are all represented by a list; a partof the mapping relationships and/or a part of the inverse mappingrelationships are represented by one computation expression or a groupof computation expressions while the others are represented by a list.

Embodiment 5 for the Mapping of the Value Range of Matching RelationshipParameters

The mapping relationship and/or the inverse mapping relationship of oneof the foregoing mappings (or the foregoing partial mappings) and/or theforegoing inverse mappings (or the foregoing partial inverse mappings)in the value range or the subordinate value range change as the statusand/or parameters of current coding (decoding) change.

Embodiment 6 for the Mapping of the Value Range of Matching RelationshipParameters

The mapping relationship and/or the inverse mapping relationship of oneof the mappings (or the foregoing partial mappings) and/or the foregoinginverse mappings (or the foregoing partial inverse mappings) in thevalue range or the subordinate value range change as the width of thecurrent CU changes, that is, when a width of a current CU is a value, amapping relationship and/or an inverse mapping relationship are used;when a width of a current CU is another value, another mappingrelationship and/or inverse mapping relationship are used, for example,if the width of the current CU is W, the frequencies of a plurality ofor all the multiples of the value W of a certain matching relationshipparameter (e.g. a matching distance) are much greater than those of aplurality of or all the multiples of values different from W, then it isneeded to map the plurality of or all the multiples of the value W tovalues in a smaller value range and those of the values different from Wto values in a bigger value range so that the mapping relationship isrelated to W, as a result, when the W changes, the mapping relationshipchanges, and so does the inverse mapping relationship.

Embodiment 7 for the Mapping of the Value Range of Matching RelationshipParameters

As a special case of embodiment 6, in this embodiment, one of thematching relationship parameters is a matching distance, and the width Wof the current CU has four values: 64, 32, 16 and 8, and accordingly,the mapping or the inverse mapping has four mapping relationships and/orfour inverse mapping relationships.

Embodiment 8 for the Mapping of the Value Range of Matching RelationshipParameters

Apart from the foregoing modules, there is further a real-time statisticmodule for various values in the value range of matching relationshipparameters, arranged to make real-time statistics on the characteristicsof various values, for example, the frequency at which each of thevalues appears till the current moment; and dynamically adjust themapping relationship of the foregoing mapping (or the foregoing partialmapping) and/or the inverse mapping relationship of the inverse mapping(or the partial inverse mapping) according to the result of thereal-time statistics on the various values of the matching relationshipparameters.

In conclusion, the image coding and decoding methods and apparatusproposed in the embodiments of the present document improve imagecompression performance.

In still another embodiment, software is also provided which is used forexecuting the foregoing embodiments and the technical solutionsdescribed in the foregoing embodiments.

In still another embodiment, a storage medium is also provided in whichthe foregoing software is stored, including, but not limited to anoptical disk, a floppy disk, a hard disk and erasable memory etc.

Apparently, it should be appreciated by those skilled in the art thateach module or each step described in the present document can berealized by a universal computing device and that the modules or stepsmay be integrated on a single computing device or distributed on anetwork consisting of a plurality of computing devices, alternatively,the modules or steps may be realized with program codes executable by acomputing device, so that the modules or steps can be stored in astorage to be executed by a computing device. In some cases, the stepsshown or described herein can be executed in a sequence different fromhere, or the modules or steps are formed into various integrated circuitmodules, or several of the modules or steps therein are formed into asingle integrated circuit module. Therefore, the present document is notlimited to any specific combination of hardware and software.

The above description is only alternative embodiments of the presentdocument, and is not used for limiting the present document. For thoseskilled in the art, there can be a variety of modifications andvariations. Any modification, equivalent substitute and improvement madewithin the essence and principle of the present document shall fallwithin the protection scope of the present document.

INDUSTRIAL APPLICABILITY

The present document relates to the compression coding and decoding ofdigital videos and provides an image coding and decoding method andapparatus, herein the image coding method includes: performing matchingcoding on pixels of an input video image to obtain one or more matchingrelationship parameters, herein the matching relationship parameters areparameter used in a process of constructing predicted values and/orreconstructed values of the pixels in image; mapping the matchingrelationship parameters to obtain mapped value of the matchingrelationship parameters; and performing entropy coding on the mappedvalue of the matching relationship parameters. The present documentaddresses the problem existing in the conventional art which is causedby the direct implementation of entropy coding for matching relationshipparameters and achieves a good data compression performance throughentropy coding.

What is claimed is: 1-21. (canceled)
 22. An image coding method,comprising: performing matching coding on pixels of an input video imageto obtain one or more matching relationship parameters, wherein thematching relationship parameters are parameters used in a process ofconstructing predicted values and/or reconstructed values of the pixelsin the input video image; mapping the matching relationship parameter toobtain a mapped value of the matching relationship parameter; andperforming entropy coding on the mapped value of the matchingrelationship parameter.
 23. The method according to claim 22, whereinmapping the matching relationship parameters comprises: converting,according to existing matching relationship parameters, matchingrelationship parameters to be matched, and taking values obtained afterthe conversion as the mapped values of the relationship parameters to bematched; and/or assembling and/or rearranging matching relationshipparameters of a same type into a matching relationship parameter groupaccording to a specific rule, mapping the matching relationshipparameter group, and taking the matching relationship parameter groupobtained after the mapping as the mapped values of the matchingrelationship parameters.
 24. The method according to claim 23, whereinthe specific rule includes at least one of the following rules: a presetrule; and an operation which is set according to a value of the existingmatching relationship parameter for assembling and/or rearranging aplurality of relationship parameters to be matched.
 25. The methodaccording to claim 23, wherein mapping the matching relationshipparameter group comprises: taking values of the matching relationshipparameters in the matching relationship parameter group as an output ofthe mapping; and/or taking values obtained after converting the valuesof the matching relationship parameters in the matching relationshipparameter group as an output of the mapping.
 26. An image decodingmethod, comprising: performing entropy decoding on a received bitstreamto obtain values of fields for indicating matching relationshipparameters, wherein the matching relationship parameters are parametersused in a process of constructing predicted values and/or reconstructedvalues of pixels in a video image to be decoded; mapping the values ofthe fields to obtain mapped matching relationship parameters; andconstructing the predicted values and/or the reconstructed values of thepixels in the video image to be decoded according to the mapped matchingrelationship parameters.
 27. The method according to claim 26, whereinmapping the values of the fields to obtain mapped matching relationshipparameters comprises: converting, according to the obtained matchingrelationship parameters, the values of the fields to be processed, andtaking values obtained after the conversion as the mapped matchingrelationship parameters; and/or assembling and/or rearranging the valuesof the fields to be processed of a same type into an array according toa specific rule, and processing the array as the mapped matchingrelationship parameters.
 28. The decoding method according to claim 27,wherein the specific rule includes at least one of the following rules:a preset rule; and an operation which is set according to the obtainedvalue of the field for assembling and/or rearranging the values of thefields to be processed.
 29. The method according to claim 27, whereinprocessing the array comprises: taking values of the fields to beprocessed in the array as output values after processing; and/or takingvalues obtained after converting the values of the fields to beprocessed in the array as output values after processing.
 30. An imagecoding apparatus, comprising: a matching coding module arranged toperform matching coding on pixels of an input video image to obtain oneor more matching relationship parameters, wherein the matchingrelationship parameters are parameters used in a process of constructingpredicted values and/or reconstructed values of the pixels in the inputvideo image; a mapping module arranged to map the matching relationshipparameters to obtain mapped values of the matching relationshipparameters; and an entropy coding module arranged to perform entropycoding on the mapped values of the matching relationship parameters. 31.An image decoding apparatus, comprising: an entropy decoding modulearranged to perform entropy decoding on a received bitstream to obtainvalues of fields for indicating matching relationship parameters,wherein the matching relationship parameters are parameters used in aprocess of constructing predicted values and/or reconstructed values ofpixels in a video image to be decoded; a mapping module arranged to mapthe values of the fields to obtain mapped matching relationshipparameters; and a construction module arranged to construct thepredicted values and/or the reconstructed values of the pixels in thevideo image to be decoded according to the mapped matching relationshipparameters.